fix(srt): keep the fabric reference constant importable on Python 3.10

The binder runs in srtctl's Python 3.10 venv, where importing infx.clusters fails on typing.Self.

Author: adibarra

inferencex-e2e/infx/clusters/slurm.py

@@ -13,6 +13,7 @@
 from pydantic import AfterValidator, Field, PlainSerializer, field_validator, model_validator
 
 from infx.clusters.base import Record, SchedulerSettings, Visibility, Volume
+from infx.srt_slurm.workload import FABRIC_REFERENCE
 
 if TYPE_CHECKING:
     from infx.clusters import Cluster
@@ -157,7 +158,6 @@ def _repository_relative(cls, script: PurePosixPath) -> PurePosixPath:
     tuple[FabricName, ...], Field(min_length=1), PlainSerializer(",".join, return_type=str)
 ]
 FabricNumber = Annotated[int, Field(ge=0), PlainSerializer(str, return_type=str)]
-FABRIC_REFERENCE = "@fabric."
 
 
 class Fabric(Record):

inferencex-e2e/infx/matrix/generate.py

@@ -12,8 +12,9 @@
 import yaml
 
 from infx.clusters import CLUSTER_LABEL_PREFIX
-from infx.clusters.slurm import FABRIC_REFERENCE, Fabric
+from infx.clusters.slurm import Fabric
 from infx.srt_slurm.variants import deep_merge, expand_variants
+from infx.srt_slurm.workload import FABRIC_REFERENCE
 
 from .validation import (
     DEFAULT_AGENTIC_DURATION_SECONDS,

inferencex-e2e/infx/srt_slurm/workload.py

@@ -18,10 +18,12 @@
 
 import yaml
 
-from infx.clusters.slurm import FABRIC_REFERENCE
 from infx.config import repository_root
 from infx.srt_slurm.synthetic_acceptance import selected_recipes, spec_parameters
 
+# Defined here: srtctl's venv runs this module on Python 3.10, so it cannot import infx.clusters.
+FABRIC_REFERENCE = "@fabric."
+
 # Keyed by (agentic, multinode).
 SHARED_BLOCKS = {
     (False, False): Path("configs/srt-recipes/fixed-sequence-single.yaml"),